Ph.D, MSc

Dr. Murugadass K. currently serves as Assistant Professor in Physics, Department of Sciences, School of Engineering, Coimbatore Campus. His areas of research include Condensed Mater Physicist Electro Optics.


Publication Type: Journal Article

Year of Publication Title


R. Rajanandkumar, N Prabu, P. Sathya, Dr. Murugadass K., and Mohan, M. L. N. Madhu, “A study on polymorphism of hydrogen-bonded thermotropic liquid crystals”, Phase Transitions, pp. 1–16, 2015.[Abstract]

A novel mesogenic homologous series comprising of eight hydrogen-bonded liquid crystalline complexes are isolated and analyzed by forming a hydrogen bond between p-n alkyloxy benzoic acids (where n represent alkyloxy carbon number which varies from 5 to 12) and mesaconic acid, respectively. Eight synthesized complexes are subjected to Fourier transform infra-red spectroscopy, polarizing optical microscopy and differential scanning calorimetry studies to meet the basic characterization. The variation of optical tilt angle with respect to temperature in various conventional and smectic X phases are investigated and analyzed. A phase diagram is constructed to elucidate the mesogenic behavior of novel liquid crystalline series. The Cox ratio that reveals the order of various mesophases and the stability factor, to invoke the thermal stability of mesophases, is studied under the results of DSC thermogram. More »»


Dr. Murugadass K., “Design synthesis and characterization of hydrogen bonded ferroelectric liquid crystals formed by levo tartaric acid and alkyloxy benzoic acids”, 2014.[Abstract]

Design synthesis and characterization of Hydrogen Bonded Liquid newlineCrystals HBLC play a vital role in the development of soft materials for newlinevarious applications Especially the characterizations of Ferroelectric Liquid newlineCrystals FLC have great implication to fulfil the current challenges in display newlinedevices materials With this insight the present study is intended to design newlinesynthesize and characterize three novel series of hydrogen bonded compounds newlineincluding chiral homologues These compounds are characterized by newlinespectroscopic studies FTIR and NMR thermal studies Polarizing Optical newlineMicroscopy POM Differential Scanning Calorimetric study DSC and Optical newlinetilt angle measurements Further the variation of dielectric permittivity with newlinetemperature and dielectric relaxation studies in various mesophases are also newlinecarried out to detect the phase transition temperatures and corresponding newlineArrhenius energies The growth of selected mesophases has been studied by newlinecrystallization kinetics newlineDesign synthesis and characterization of various Hydrogen Bonded newlineLiquid Crystals HBLC have been undertaken Three series of compounds newlinenamely levo tartaric acid and pn alkoxy benzoic acid homologous series newlineLTAnBAO where n represent alkoxy carbon number dodecyl aniline and piv newlinen alkoxy benzoic acid homologous series 12A12BAO and hexadecyl aniline newlineand pn alkoxy benzoic acid homologous series 16A12BAO have been newlineisolated The synthesis route involves mixing of equimolar ratios of pn alkoxy newlinebenzoic acid and the other ingredients The first series LTAnBAO is newlineferroelectric with four compounds exhibiting various orthogonal and tilted newlinephases the latter two series 12AnBAO 16AnBAO comprise of sixteen newlinedifferent compounds exhibiting rich phase polymorphism FTIR and NMR newlinestudies on these compounds infer the formation of hydrogen bond newlineConventional phases like Cholestric Nematic Smectic C Smectic F and newlineSmectic G phases are recorded and identified with the standard textures More »»


Dr. Murugadass K., Vijayakumar, V. N., and Mohan, M. L. N. Madhu, “Ambient Smectic Ordering in Hydrogen-Bonded Liquid Crystal Homologous Series”, Molecular Crystals and Liquid Crystals, vol. 537, pp. 22–35, 2011.[Abstract]

A homologous series of compounds with an inter-hydrogen bond formed between p-n-alkyloxy benzoic acids (nABA) and alkyl aniline were synthesized and characterized. The mesogenic p-n-alkyloxy benzoic acids (where n represents the alkyloxy carbon number from 3 to 12 except 4 and 6) formed a hydrogen bond with liquid-crystal intermediate 4-dodecyl aniline. The isolated homologous series compounds were analyzed by polarizing optical microscopy (POM), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance (P-NMR), and dielectric studies. The occurrence of an ambient smectic ordering in some of the isolated mesogens was one of the interesting features of these homologous series. The phase diagrams of the p-n-alkyloxy benzoic acids and the present homologous series were computed and compared and it can be mentioned that there exists a correlation between the alkyl chain length and mesogenic phases induced. Further, some of the mesogens exhibit monotropic smectic F and smectic G transitions. The hydrogen bond formation was evinced through FTIR and P-NMR spectral studies. Results of free p-n-alkyloxy benzoic acids and the hydrogen-bonded homologous series are discussed in the light of increment alkyloxy carbon number, mesogenic phases exhibited, and mesogenic thermal range. More »»


V. N. Vijayakumar, Dr. Murugadass K., and Mohan, M. L. N. Madhu, “A study of reentrant smectic ordering in hydrogen bonded ferroelectric dodecyloxy benzoic acid and tartaric acid liquid crystal”, Molecular Crystals and Liquid Crystals, vol. 517, pp. 43–62, 2010.[Abstract]

A linear hydrogen bonded homologous liquid crystal series has been isolated with chiral ingredient as levo tartaric acid possessing two chiral carbons and non chiral mesogen as p-n-alkoxy benzoic acids. In the synthesized hydrogen bonded complexes the p-n-alkoxy benzoic acid moiety varied from pentyloxy to dodecyloxy with an exception of butyloxy and hexyloxy benzoic acids. Textural studies have been carried out by polarizing microscopic studies, (POM). Interestingly the phase sequences exhibited by odd and even complexes are strikingly different. In other words phase sequence of Nematic, smectic C*, F*, and G* is observed in the odd hydrogen bonded complexes while in addition to these phases the even counter parts exhibit a new type of phase sequence with smectic C* followed by pseudo smectic C* and reentrant smectic C* phases which are designated as Sm C*, Sm C p *, and Sm C r * phases respectively. A detailed DSC and dielectric studies confirmed the existence of the reentrant phase. We report a new phase which looks like a long worms and designated it as the pseudo smectic C p *. Theoretical arguments are presented towards the existence of reentrant phenomenon. The magnitude and order of the optical pitch in this phase is almost identical to that of traditional smectic C* phase. Phase diagram is constructed for the homologous series. Results of tilt angle, dielectric relaxations and dielectric permittivity variations are discussed. More »»


V. N. Vijayakumar, Dr. Murugadass K., and Mohan, M. L. N. Madhu, “Study of intermolecular hydrogen bonding in pn-alkoxybenzoic acids and alkyl aniline homologous series–part I”, Molecular Crystals and Liquid Crystals, vol. 515, pp. 39–48, 2009.[Abstract]

A homologous series of interhydrogen bonded complexes between p-n-alkoxybenzoic acids (nABA) and alkyl anilines were isolated. The mesogenic nABA (where n represents the alkoxy carbon number from 5 to 12 except 6) formed a hydrogen bond with liquid crystal intermediate 4-hexyl aniline. The homologous series mesogens are analyzed by polarizing optical microscope, differential scanning calorimetry (DSC), and FTIR studies. An interesting feature of these homologous series is the drastic reduction of the mesogenic temperatures and the occurrence of smectic ordering just above ambient temperature. The phase diagrams of the nABA and the homologous series were computed and compared, respectively. A critical observation in all the binary compounds of the present homologous series reveals that there exists a correlation between the alkyl chain length and mesogenic phases induced. Further some of the mesogens exhibit monotropic Smectic F and Smectic G transition. The hydrogen bond formation was evinced through FTIR spectral studies. Results of free nABA and the hydrogen bonded homologous series were discussed in the light of increment in alkoxy carbon number, mesogenic phases exhibited, and mesogenic thermal span. More »»


V. N. Vijayakumar, Dr. Murugadass K., and Mohan, M. L. N., “Inter hydrogen bonded complexes of hexadecylaniline and alkoxy benzoic acids: a study of crystallization kinetics”, Brazilian Journal of Physics, vol. 39, pp. 600–605, 2009.[Abstract]

A systematic crystallization kinetic study of two smectogens of homologous series of the inter molecular hydrogen bonded between undecyl, dodecyl benzoic acids and hexadecylaniline complexes viz., 16A+11BA and 16A+12BA respectively has been carried out by thermal microscopy, differential scanning calorimetry (DSC) and dielectric studies. FTIR studies indicate the formation of hydrogen bond in these complexes. The crystallization kinetics was studied by two techniques viz., the traditional thermal analysis (DSC) and electrical studies in which capacitance and dielectric loss variation with temperature were recorded and analyzed. The DSC thermograms were run from crystallization temperature to the isotropic melt for different time intervals. The liquid crystalline behaviour together with the rate of crystallization of smectic ordering in newly synthesized inter hydrogen bonded complexes were discussed in relation to the kinetophase (which occurs prior to the crystallization). The molecular mechanism and dimensionality in the crystal growth were computed from the Avrami equation. The characteristic crystallization time (t*) at each crystallization temperature was deduced from the individual plots of log t and ∆H. Further, it was observed that the data obtained from DSC and dielectric studies were in good agreement with one another. For the first time in the history of crystallization studies, crystallization kinetics data is experimentally elicited from a novel dielectric technique. More »»

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